Mysterious type t_RFRAC and denominator function

[Jacques Gélinas <jacquesg00@hotmail.com>]

What is "t_RFRAC" or a denominator exactly ?

# type(a/b)
%1 = "t_POL"
# type(b/a)
%2 = "t_RFRAC"
# denominator(a/b)
%3 = 1
# denominator(b/a)
%4 = a

Can one conclude that the symbol "a' is treated differently than the symbol "b" ?

Jacques Gélinas